The disparity raises questions about how the team should proceed if doctors clear starter Kevin Kolb to return this week from a concussion. The numbers say Kolb or just about anyone else should start, but the team might want to keep Skelton around for fourth quarters and overtimes.

Skelton, who played a leading role in the Cardinals' comeback from a 10-point, fourth-quarter deficit Sunday, owns four game-winning drives after third quarters in his last eight appearances. But he has been much worse than average earlier in games.

In fact, Skelton ranks last among 36 qualifying quarterbacks in first-quarter Total QBR this season, posting a 6.3 score that lags far behind average (50) on a 100-point scale. Skelton improves to 28th in second quarters (32.0) and 28th in third quarters (35.9) before making a striking transformation. Skelton ranks 12th in fourth-quarter QBR (66.5) and ninth in fourth quarters and overtimes combined (71.4).

Tebow outranks Skelton in fourth-quarter QBR, 73.5 to 66.5, but Skelton has done more to help his team win in overtimes.. The Cardinals are 3-0 in overtime games this season, including 2-0 with Skelton. They visit Cincinnati in Week 16.

Quick thoughts on how NFC West passers graded out in Week 15 according to Total QBR, with NFL passer ratings in parenthesis as a reference point:

John Skelton, Arizona Cardinals (55.6 QBR, 79.3 NFL rating): Skelton completed 28 of 46 passes for 313 yards with one touchdown, one interception, four sacks and two runs covering seven yards. He did not fumble. Skelton completed passes of 21, 23 and 24 yards during a roughly two-minute period of the fourth quarter. His longest completion, a 32-yarder to Larry Fitzgerald, set up the winning field goal in overtime. Skelton completed no passes longer than 12 yards to his running backs or wide receivers before the fourth quarter. Tight end Todd Heap played a more prominent role.

Tarvaris Jackson, Seattle Seahawks (42.6 QBR, 94.4 NFL rating): Jackson completed 19 of 31 passes for 227 yards with one touchdown no interceptions, one sack and three rushes for minus-2 yards. The Bears recovered his lone fumble for a touchdown. Jackson completed 15 of 19 passes after halftime. That included a deep pass to Ben Obomanu for a 43-yard gain to the Chicago 3-yard line on the Seahawks' opening drive of the second half. Marshawn Lynch scored on the next play, tying the game and beginning a 31-0 scoring run for Seattle.

Kellen Clemens, St. Louis Rams (24.0 QBR, 95.7 NFL rating): Clemens completed 25 of 36 passes for 229 yards with one touchdown, no interceptions, three sacks and two rushes covering 9 yards. The Rams recovered his lone fumble. Clemens was impressive for a quarterback joining his team only recently. His team trailed for all but five minutes of the game, however. QBR rewards quarterbacks for improving win probability for their teams. The Rams converted twice in 13 third-down chances. They managed two first downs on three drives while the Bengals turned a 6-6 game into a 20-6 blowout. A touchdown with 1:14 remaining proved inconsequential.

The chart below shows how quarterbacks from games involving NFC West teams fared in Total QBR for Week 15.

The clutch-weight average column reflects game situations, not how well players performed during those situations. Any clutch average above 1.0 reflects a quarterback performing in higher-pressure situations.